Severe Weather October 4th -Moderate Risk Needed

This is the 00z NAM at 27 hours out or 11 PM this evening. As we will show ingredients are in place for a severe weather event to occur ..However.. the highest impacted area will be in the vicinity of the area of low pressure to the North near and around Iowa..

The culprit will be a warm front that is draped across the north and a cold front that will be moving to the east. An area of low pressure will move along this cold front and be in a position near Iowa later this evening. The air out ahead of this cold front is quite unseasonably warm for this time of the year with temperatures in the 80s

Dew points in the 60s. Almost reminds one of a summer day even though we are now in the fall season.

As we mentioned all ingredients are in place.. when you have this type of heat in place..a strong trigger , as in a cold front with much colder air behind it ..and the dynamics in the atmosphere..it spells trouble with a capital T...

Lets look at the dynamics that will be in place...

We are going to start with two images that are really kind of "serious " images and that would be the Energy Helicity Index and the Helicity image...

You can see that the EHI is well above 1 across the region of Iowa. The NAM is actually showing EHI between 6-7. This is suggestive of Tornados and some that could be long tracked tornado's.

Helicity is not much better...

As you can see the Helicity itself is quite high at 300 +. Factoring this with the EHI brings a real concern for Tornadic activity and we have this area highlighted in red on our map.
Now when you have these dynamics in place then factor in shear and CAPE or convective Potential Energy.. You have the potential for an outbreak.. And we do have the shear in place...

50-80 knots of shear forecasted to be in place. 

Convective Available Potential energy 2000 + .. Lift in the atmosphere is around -8 to -10 .

You can see why we are saying that all the ingredients are in place for a significant severe weather outbreak. And we have this area as we mentioned highlighted in red which would be a moderate risk for Tornado's, wind damage and the potential for hail.

If you reside in the red zone please keep your eyes to the sky and make sure you have your NOAA weather radio near by and please seek shelter and heed any warnings that may occur... We wish everyone in path of this storm system to stay safe...